Malva parviflora L. Leaf Aqueous Extract Assisted Green Synthesis of Gold Nanoparticles at Room Temperature and Cytotoxicity Evaluation of Nanoparticles on Cell Culture

Recently, noble metal nanoparticles such as Au, Ag, Pt, and Pd are widely developed due to their special physiochemical properties in biological applications. Among these, gold nanoparticles have been considered as an important area of research due to their unique and tunable surface plasmon resonance and their applications in biomedical science [1]. Plant mediated synthesis of AuNPs is gaining more importance over other processes because the synthetic methods involve various chemicals that may lead to the presence of toxic chemical species, which may have adverse effects in biological applications. Currently a lot of research studies leading to novel methods of green synthesis of AuNPs have been carried as these methods are cost effective, free of hazardous reagents and involve only mild reaction conditions [2, 3]. In this study, green synthesis of gold nanoparticles (AuNPs) from aqueous AuCl4- solution using aqueous extract of Malva parviflora L. was successfully carried out. The leaf aqueous extract of Malva parviflora was prepared using ultrasound-assisted extraction method. The obtained Malva parviflora L. extract is capable of in situ synthesis of red-purple color AuNPs at ambient conditions. The reaction process was monitored by using UV–vis spectrophotometry. Further characterizations of nanoparticles were carried out using TEM image and particle size analysis. The surface plasmon absorption spectrum of AuNPs exhibits only a single peak at around 545 nm. The TEM image showed that the highly dispersed AuNPs with less than 20 nm size and spherical shape were prepared which effectively considered as single particles. The effect of different variables on the biosynthesis and plasmon absorbance of AuNPs such as various volumes of extract, time and pH were studied. The results indicated that the red color AuNPs with 8 nm size and intensified plasmon absorbance bands were observed at alkaline media. Furthermore, cytotoxicity evaluation of nanoparticles denoted that the green synthesized AuNPs have low toxicity in comparison with chemically prepared AuNPs using citrate.